Controllable semiconductor component

ABSTRACT

The invention concerns a semiconductor component which can be controlled on the anode side and whose semiconductor body comprises a plurality of adjacent, parallel-connected unit cells having a thyristor structure. A lightly doped n-base region (3) is adjoined on both sides by highly doped p-regions constituting p-base region (2) and p-emitter region (4). The p-base region (2) is followed by a highly doped n-emitter (1) which contacts a cathode electrode (7). Integrated in the p-emitter region (4) is a first n-channel MOSFET (M1) which is connected in series with the thyristor structure by means of a floating electrode (FE). The drain electrode (5b) of the first MOSFET (M1) is provided with an outer anode (8) which has no contact with the p-emitter region (4). A second n-channel MOSFET (M2) is integrated between the n-base region (3) and the drain region (5b) of the first MOSFET (M1).

BACKGROUND OF THE INVENTION

The invention relates to an anode-side actuated semiconductor component,for which the semiconductor element has a plurality of side-by-sidearranged, parallel connected unit cells with thyristor structure, and tobidirectional semiconductor switches with such an anode-side actuatedsemiconductor component.

Bidirectional semiconductor components, which can be switched on and, ifpossible, also switched off by a control signal in both polaritydirections of the main electrodes are highly advantageous foralternating current uses. A frequently used component of this type isthe Triac, which comprises two antiparallel-arranged thyristorstructures and can be switched on through gate current, independent ofthe polarity sign of the voltage that is present. The Triac cannot beswitched off via the gate, but only through a polarity reversal of themain electrodes.

A component, which can be switched on as well as off by a MOS gate inboth polarity directions was described in IEEE Transactions on ElectronDevices, Vol. ED-27 (1980), pp 380-87. This so-called TRIMOS (MOS-Triac)is a lateral component, comprising two DMOS transistors in a laterallyreversed arrangement, for which the gate electrodes are mutuallyconnected. The voltage range is limited in this case by the breakdownvoltage of the gate oxide and typically only extends to about 50 V. Ifthe gate electrodes are separated and actuated individually, voltages ofup to 300 V can be reached. It is favorably in this case that thecomponent functions at higher currents like an IGBT, so that theon-resistance is reduced through conductivity modulation. However,advantages during the actuation are lost again when separating the gateelectrodes.

A bilaterally switching component with thyristor structure and laterallayout, which is referred to as BEST (bilateral emitter switchedthyristor), was presented at the International Electron Device MeetingIEDM 1992 (IEDM'92 Conference Volume, pp 249-252). The blocking capacityof the component was less than 70 V. The characteristics are comparableto those of the TRIMOS. Not only the voltage range, but also theswitchable current is narrowly limited as a result of the lateral layoutof these switching elements. A separate MOS gate is provided forswitching on and switching off in each current direction, which isactuated by the cathode electrode of the respective current direction.This is a disadvantage because of the expenditure for the driverelectronics. Such a concept is not suitable for vertical bidirectionalcomponents.

The standard power components such as the MOSFET, the insulated gatebipolar transistor or IGBT, the normal bipolar transistor and the (GTO)thyristor are actuated from the cathode and require a positive controlvoltage for the switching on. For a bidirectional switch, which referredto a (relatively small) gate signal can be switched to a fixed mainelectrode, an anode-side actuated components is necessary in addition tothe standard cathode-side actuated component. By exchanging n- andp-conductivity type in the various semiconductor zones, anode-sideactuated components are obtained from the aforementioned standardstructures. However, these have the disadvantage is that they cannot beintegrated together with the standard ones, among other things becausethe weakly doped base for absorbing the voltage has the reversedconductivity type, namely p-conductivity. A second disadvantage of thisanode-side actuated component is that the gate signal must have apolarity for the switching that is the reverse of the normal one: anegative voltage at the gate is necessary for switching on. Abidirectional switch with such individual components thus requirescontrol signals for the switching on and off, which depend on thecurrent direction, so that the control signal changes, among otherthings, for the zero passage of the current. A very involved driverelectronics is consequently required.

A MOS-controlled thyristor was suggested in the German PatentApplication P 44 02 877, which can be switched on and off in series tothe thyristor structure by a p-channel MOSFET that is integrated intothe n-emitter zone. During the switching off, a voltage that builds upat the MOSFET is transmitted as a negative gate voltage to the p-base ofthe thyristor by a second integrated MOSFET, which switches onautomatically once the first one is switched off. This permits anefficient switching off. The externally actuated MOSFET and thethyristor are integrated by using a second, internal MOSFET of the typeof a known cascode circuit. The component permits a high on-statecurrent per surface with low on-state voltage, can be used up to highblocking voltages, and has a characteristic with current limitation.

As described in this patent application, an inverse component isobtained by exchanging the n- and p-conductance in the varioussemiconductor zones, which can be actuated from the anode side. Like thestandard components, this component is switched on by positive gatevoltage and is switched off by removing or reversing the gate signal.Since it has a weakly doped p-base zone for absorbing the voltage, it isnot suited to monolithic integration together with the standardcomponents, which have a transistor or thyristor structure.

SUMMARY OF THE INVENTION

The invention is based on the general problem of creating abidirectionally driven component, which can be switched on and offthrough MOS gate and is suitable for a higher voltage and current rangethan the known components that can be switched on and offbidirectionally and which has a stable switching behavior. It must bepossible to actuate the component for both current directions from thesame main electrode, that is with the same polarity as the controlpulse.

One partial problem with the invention is in this case the creation of aMOS component that can be actuated from the anode side and can beintegrated together with traditional components having transistor orthyristor structure. Such an anode-side actuated component is importantper se, since it can be produced with technology used for standardcomponents. It should be possible to actuate the component with positivecontrol voltage (relative to the anode) and to switch it off by removingor reversing the control voltage.

The solution according to the invention for a semiconductor component ofthe aforementioned type is that higher doped p-zones as p-base zone andp-emitter zone adjoin a weakly doped n-base zone on both sides and thatthe p-base zone is followed by a highly doped n-emitter zone, contactedwith a cathode electrode, that in the p-emitter zone a first n-channelMOS field effect transistor is connected in series with the thyristorstructure by a floating electrode, that the drain electrode of the firstMOS field effect transistor has an outer anode electrode that has nocontact with the p-emitter zone, and that a second n-channel MOS fieldeffect transistor is integrated between the n-base zone and the drainzone of the first MOS field effect transistor. This semiconductorcomponent can be integrated, together with other components that areknown per se to produce specific electrical functions, specifically toproduce a bidirectional, switchable component with only one gate, whichcan be actuated with the same voltage, independent of the currentdirection.

For one preferred embodiment, the insulated gate for the second MOSfield effect transistor, which is located above the p-region between then-base and the n⁺ -region, is connected with the outer anode. Since theabove-described component is a special type of an inverse,cascode-switched MOS thyristor, it is henceforth designated with theabbreviation ICMT. The MOS field effect transistor is in the followingcalled a MOSFET.

Even though the ICMT is an inverse component, the weakly doped n-basezone and the higher doped p-zones that adjoin on both sides, as well asthe following n⁺ -zones, result in a design with a structure thatcorresponds largely to that of standard transistor or thyristorcomponents. The anode-side actuated component therefore can easily beintegrated with standard components on a semiconductor chip. The ICMT asindividual component can be produced economically with technology usedfor the standard components.

One preferred embodiment provides that the division into unit cells isthrough a trough-shaped embodiment for the p-emitter zone, that twospaced apart n⁺ -zones are embedded into the p-emitter zone parallel toits edge on at least one side, that the n⁺ -zones with the interposedp-region of the p-emitter zone and an above-arranged insulated gateelectrode form the first n-channel MOS field effect transistor, that theone n⁺ -region adjoining the edge of the trough-shaped p-emitter zone,together with the n-base zone that emerges at the surface and thesegment of the p-emitter zone that is located between them as well as anabove-arranged gate electrode form the second n-channel MOS field effecttransistor, that the other n⁺ -zone and the p-emitter zone have a jointfloating electrode, and that the n⁺ -zone that adjoins the edge isconnected to the outer anode electrode, which has no contact with thep-emitter zone.

An ICMT of the above-described type can be realized either with lateralor vertical thyristor structure. For a vertical embodiment, then-emitter zone, the p-base zone, the n-base zone, the p-emitter zone andthe anode contact are arranged one above the other, wherein the cathodecontact connected to the n-emitter zone is located on the lower limitinglevel and the anode electrode as well as the gate electrode are arrangedon the upper limiting level of the semiconductor element.

For a lateral embodiment, the weakly doped n-base zone is arranged on asubstrate, from which it is separated by an insulating layer or apn-junction. The p-base zone and the p-emitter zone are embedded in theshape of a trough into the n-base zone, at a lateral distance that ispredetermined by the blocking capacity. The n-emitter zone is embeddedinto the p-base zone and the source and drain zones for the first MOSfield effect transistor are embedded into the p-emitter zone.

The series-connected thyristor must be ignited so that the component isactivated when the first MOSFET is switched on and a negative voltage ispresent at the cathode. The thyristor can be ignited by designing itsuch that it blocks per se in the switching direction. However, it ispreferable if the thyristor has a forward blocking capacity. In thatcase, it is provided in accordance with the invention with a specialdevice for igniting it through the gate on the anode side, withoutaccess to the n- and p-base zones. Such an ignition arrangement isembodied in that at a larger distance from the region with unit cellsand separated from these or by interrupting the p-emitter zone, anignition region is provided in the semiconductor element, whichcomprises a p-emitter zone with bordering n-base zone, the followingp-base zone and the subsequently following n-emitter zone, wherein thep-emitter zone is provided with an ignition gate contact and has a n⁺-zone, for which the contact electrode is connected to the floatingelectrode, but does not short-circuit the pn-junction in the ignitionregion between the p-emitter zone and the embedded n⁺ -zone. With theaid of this ignition region, the semiconductor element can be switchedon and off by the gate. An alternative arrangement for switching on thethyristor structure provides for a surface channel zone at the edge ofthe semiconductor element, which connects the p-emitter zone with thep-channel zone, but which is interrupted in the switched-off position bythe voltage that develops at a MOS gate.

One preferred lateral embodiment of the semiconductor element that canbe switched on and off by MOS gate and is actuated from the anode sideis described.

A bidirectional semiconductor switch according to the invention isdesigned such that an anode-side actuated semiconductor component of theabove described type is arranged in a hybrid circuit, together with acathode-side actuated semiconductor component that is known per se. Withsuch a semiconductor component, the anode connection for the anode-sideactuated semiconductor component and the cathode connection of thecathode-side actuated semiconductor component are connected to form ajoint first main electrode and the cathode of the anode-side actuatedsemiconductor component as well as the anode of the cathode-sideactuated semiconductor component are connected to form a second mainelectrode. The gate electrodes for the two semiconductor components arepreferably combined to form a joint gate electrode.

A monolithically integrated, bidirectionally switchable semiconductorcomponent according to the invention is designed such that unit cells ofthe anode-side actuated semiconductor component of the above describedtype are arranged in a semiconductor element with unit cells of acathode-side actuated semiconductor component and that the unit cells ofthe anode-side actuated semiconductor component are arranged in a firstregion and the unit cells of the cathode-side actuated semiconductorcomponents are arranged in a second region of the semiconductor element.The unit cells of the known cathode-side actuated semiconductor elementin the second region preferably form an insulated gate bipolartransistor (IGBT) with an anode side p-zone, a n-base zone and acathode-side p-zone, into which an n⁺ -zone is embedded and which,together with the n-base zone, the cathode-side p-zone region locatedbetween and an insulated gate, form an MOS field effect transistor,wherein the cathode-side electrode with the anode electrode and theanode-side electrode with the cathode electrode of the anode-sideactuated semiconductor component and the gate electrode of theanode-side actuated semiconductor component are preferably connected toform a joint gate electrode.

If the thyristor structure is designed without forward blockingcapacity, the n-emitter zone and the p-base zone of the anode-sideactuated semiconductor component in the first region are separated fromthe anode-side p-zone of the cathode-side actuated semiconductorcomponent in the second region in the border area between the first andsecond regions to avoid a short-circuit. Various suitable means for theseparation are described.

As an alternative to the above described embodiment, an ignition gatecan be provided in a region separated from or positioned at a distanceto the first region, which has a p-zone with gate contact embedded in atrough shape in the n-base zone, which gate contact is connected to thegate electrode of the anode-side actuated component and whichfurthermore has a second p-zone embedded into the n-base zone, which isconnected to the first p-zone by a depletion-type MOS field effecttransistor and comprises a n⁺ -zone with a contact electrode, whereinthis contact electrode is connected to the floating electrode and thegate electrode of the depletion-type MOS field effect transistor isconnected to the contact electrode of a p-zone additionally embeddedinto the n-base zone that is positioned in the space charge regionsurrounding the pn-junction for the reverse blocking operation of theanode-side actuated component.

An additional bidirectionally switchable semiconductor componentaccording to the invention is composed of a single group of unit cellsof the above described type that are themselves bidirectionallyswitchable and originate with the above-described ICMT unit cells, inthat some segments of the n-emitter zone and the p-base zone arereplaced by a p-zone that adjoins the cathode metallization, which isseparated in the above-described manner from the n-emitter zone andp-base zone, wherein the anode metallization and the cathodemetallization are connected to a first and second main electrode and thegate electrode is separated from the second main electrode and isconnected to a gate connection that is separate from the gate connectionfor the first MOSFET, so that if the second MOS field effect transistorgate is conductively connected to the first main electrode, the functionof the anode-side actuated semiconductor component that can be switchedthrough the first MOS field effect transistor gate is maintained andwith a positive actuation of the gate for the first MOS field effecttransistor, the function of the insulated gate bipolar transistor thatcan be switched on the cathode side by the gate for the second MOS fieldeffect transistor is maintained.

In this embodiment, each unit cell is designed as bidirectional switchper se, which can switch the current on and off in both flow directions.A significant advantage of this embodiment is that it requires lesssemiconductor surface space.

The invention is described in more detail below with the aid ofexemplary embodiments shown in a drawing, from which further details,features and advantages follow.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a section of a unit cell for an inventive, anode-side actuatedMOS component (ICMT element) that can be integrated.

FIG. 2 is a section of a region of an anode-side actuated, integratableMOS component, which has a gate electrode for the ignition.

FIG. 3 showing the border region of an anode-side actuated, integratableMOS component for ignition with an MOS gate.

FIG. 4 showing an anode-side actuated, laterally integratable component.

FIG. 5 illustrates a bidirectional component, comprising a unit cellaccording to FIG. 1 and an IGBT unit cell;

FIGS. 6a-d show the bidirectional component according to FIG. 4 invarious operating conditions, with;

FIG. 6a showing the bidirectional component in the forward blockingcondition (operating point on the blocking characteristic in firstquadrant);

FIG. 6b showing the bidirectional component in the forward on-statecondition (operating point on the forward characteristic in firstquadrant);

FIG. 6c showing the bidirectional component in the reverse blockingcondition (operating point on the blocking characteristic in thirdquadrant) and;

FIG. 6d showing the component in on-state condition (operating point onthe on-state characteristic in third quadrant).

FIG. 7 illustrate a section of a segment of a bidirectional componentwith non-shortened pn-junction at a main electrode.

FIG. 8 illustrate a section of a specially designed ignition region ofan anode-side actuated MOS component, which is used to prevent aswitching-on during reverse loads.

FIG. 9 illustrate a section of a unit cell with bidirectional switchingcapability.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a sectional cut of a unit cell for an inventive, anode-sideactuated semiconductor component. The unit cell comprises a weakly dopedn-base zone 3, which is joined below and above by higher doped p-zones 2or 4.

The lower p-zone 2 is followed below by a highly doped n⁺ -zone 1. Thiszone represents the cathode emitter of a thyristor structure, formed bythe layer sequence 1, 2, 3, 4. The upper p-zone 4 is shaped like atrough, and formed in the n-base zone 3 such that the n-base zone 3 onthe sides emerges at the upper major surface of the device. Two n⁺-zones 5a, 5b are embedded into the p-trough 3 for each half a unitcell. The portion of p-region in-between the zones 5a and 5b is providedwith an insulated gate electrode 6 in the surface of the devices; sothat a lateral n-channel MOSFET M1 is formed. The insulating layerunderneath the gate electrode 6 as a rule is composed of silicondioxide, the gate electrode 6 of doped polysilicon. The n⁺ -zone 1 iscovered with a cathode metallization 7 that is connected to a cathodeconnection K. The anode emitter zone 4 of the thyristor that emerges onthe surface beside the MOSFET region has a floating connecting electrodeFE, which simultaneously makes contact with the neighboring n⁺ -zone 5aof the MOSFET Ml and thus connects the vertical thyristor 1, 2, 3, 4with the lateral MOSFET Ml from the zones 5a , 4, 5b. The n⁺ -region 5bof MOSFET Ml that faces away from the connecting electrode FE has ananode contact 8 that is connected to the outer anode connection A andwhich has no contact with the anode emitter zone 4 of the thyristor. Thegate electrode 6 of the MOSFET Ml is connected to the gate connection G.

The unit cell of the inverse component according to FIG. 1 alsocomprises a second MOSFET M2, which is formed by the n⁺ -zone 5b, whichis provided with the anode contact and positioned at the edge of thep-trough, the n-base zone 3 that is pulled to the surface and the regionof p-zone 4 that is located in-between the zone 5b and the zone 3 of thesurface and for which the insulated gate electrode 9 is connected to thezone 5b and the zone 3 of the surface outer anode contact 8 of the n⁺-zone 5b or is also formed by it.

The structure according to FIG. 1 generally must be understood to behalf a unit cell, from which a complete unit cell is formed through alaterally reversed arrangement. Such a cell referred to as an ICMT alsocomprises a second pair of n⁺ -zones at the side opposite the p-trough,so that the MOSFETs M1 and M2 extend there as well.

The component according to FIG. 1 is based on a modification of thecomponent described in the above mentioned German Patent Application P44 02 877, which we hereby refer to, in order to create an inversecomponent that can be integrated with standard switching components.Instead of being integrated into the n-emitter zone of the thyristor inthe aforementioned patent application, the MOSFET M1, which is connectedin series with the thyristor, is in this case integrated into the anodeemitter zone and is designed as an n-channel MOSFET. Embodiments forswitching on and obtaining a stable reverse blocking behavior aredescribed in the following. As previously mentioned, the unit cell canbe viewed as a cascode-type integration of a thyristor with a MOSFET(M1). In addition to the desired anode-side actuation and integratingability, this embodiment of the component has the advantage that theMOSFET Ml that is connected in series with the thyristor is then-channel type, which has a charge carrier mobility that is higher by afactor of 3 to 4 than that of a p-channel MOSFET. However, thecathode-side npn-transistor, which now cannot be accessed through thegate, has a higher current amplification factor and a higher avalanchemultiplication factor than a pnp-transistor. For a predetermined voltageto be switched, the n-base zone 3 must therefore be selected to bethicker than in the other case.

In order to explain the function, the case must initially be viewed forwhich the cathode connection K relative to the anode connection A isswitched onto positive potential. If the MOSFET M1 is switched on, thecomponent then has the blocking capacity of the reverse polarizedthyristor 1, 2, 3, 4. The voltage is absorbed almost completely by theanode-side pn-junction J₁ between the n-base zone 3 and the p-zone 4,since the pn-junction J₃ that is also polarized in blocking directionfor the most part blocks only about 10 V between the n⁺ -zone 1 and thep-zone 2 because of the relatively high doping of the p-zone 2. Blockingcurrent and breakdown voltage of the component are therefore essentiallydetermined by the pnp-transistor 2, 3, 4, which is connected in serieswith the avalanching pn-junction J₃. If the MOSFET Ml is switched off,then the pn-junction J₅ between the p-zone 4 and the n⁺ -zone 5b is alsopolarized in forward direction, in addition to the junction J₂ betweenthe n-base zone 3 and the p-zone 2. To be sure, the structure continuesto block with the pn-junction J₁, but breakdown voltage and blockingcurrent are now essentially provided by the forward blocking capacity ofthe thyristor structure 2, 3, 4, 5b.

When designing an anode-side actuated component according to FIG. 4, thereverse blocking capacity of the ICMT is improved by switching on abypass from the n-base zone 3' to the cathode contact 7'. The sameelements in FIGS. 1 and 4 are provided with the same reference numbers.The design according to FIG. 4 is described in more detail below.

For V_(K) >V_(A), the MOSFET M2 for the arrangement shown in FIG. 1 isswitched off, regardless of whether the MOSFET M1 is switched on or notbecause the gate 9 is lying at the potential for electrode 8 or theanode contact 8, which in this case constitutes the source for theMOSFET M2. Thus, the ICMT component is blocking with a positivepotential at the cathode connection K, relative to the anode connectionA, regardless of how the gate G is actuated. It is presumed here thatthe thyristor structure 2, 3, 4, 5b has a forward blocking capacity.This must be achieved without short-circuiting the pn-juncture J₅, sincethis junction must block in order to switch on the MOSFET M2.

Through a high integral doping concentration N_(ip4) of the p-zone 4below the n⁺ -zone 5b and low thickness of zone 5b , it is possible toobtain a stable forward blocking behavior of the thyristor 2, 3, 4, 5b,meaning a stable reverse blocking behavior of the ICMT if the MOSFET M1is switched off, since the current amplification factor α_(n+pn) of then⁺ pn-transistor 5b, 4, 3 is very low in that case. N_(ip4) ispreferably selected larger than about 2*10¹⁴ cm² for this.

If the cathode connection K relative to the anode connection A is lyingat a negative potential and the MOSFET M1 is switched off, then theanode-side pn-junction J₅ is polarized in the blocking direction, andthe p-zone 4 receives a negative potential as compared to the gateelectrode 9. This potential, when taken absolute, adjusts to a valuesomewhat above the threshold voltage of the MOSFET M2, so that it isswitched on and frees a bypass from the n-base zone 3 to the anodecontact 8. If the MOSFET M1 is switched off, the blocking capacity ofthe ICMT is therefore not provided by the MOSFET M1 that blocks onlyslightly, but by the n⁺ pn-transistor 1, 2, 3, which has a low-ohmicconnection to the anode 8 and a high blocking capacity via thepn-junction J₂. A precondition for this is that the breakdown voltage ofthe pn-juncture J₅ is clearly higher than the threshold voltage of M2.This is adjusted through the doping of the p-zone, near the pn-junctionJ₅ and on the surface, below the gate oxide. The breakdown voltage is,for example, 12 V, while the threshold voltage is 3 V.

However, if the cathode potential is smaller than the anode potential,meaning V_(K) <V_(A), but the MOSFET M1 is switched on, then thethyristor structure below the floating electrode FE is stressed inforward direction. In this case, the MOSFET M2 is switched off becausethe p-zone 4 is lying at nearly the same potential as the gate electrode9. If the thyristor structure that is not short-circuited here does nothave forward blocking capacity or if it is switched on simultaneouslywith the MOSFET M1 by an additional ignition gate, which is describedlater on, then the component is in the on-state condition. In order toobtain a low on-state voltage, it is also desirable to have a highintegral doping N_(ip4) of the p-region 4, which functions as previouslymentioned to obtain a stable reverse blocking capacity. A high N_(ip4)results in a small current amplification factor α_(npn+) for theparasitic transistor 3, 4, 5b , which prevents too many electrons fromflowing unused through the transistor 3, 4, 5b powered up by holecurrent to the anode contact. A high α_(npn+) would for the most partruin the effect of the MOSFET M2, which is switched off in the on-statecondition, and would lead to a high on-state voltage.

If the MOSFET M1 is switched off while the component is in the on-statecondition, then this results in a switching on of the MOSFET M2,analogous to the stationary blocking condition, since in this case thepn-junction J₅ is also polarized in blocking direction by the chargecarriers, which can no longer drain off through M1. The excess electronsin the structure here can drain off via the n-channel to the anodecontact A. This bypass is no less important for the switching offoperation than for the blocking condition, since the charge carriersthat are stored during the on-state phase around the pn-junction J2 mustbe drained off so that the space-charge region around J2 can build up.Without the bypass via the MOSFET M2, a voltage could build up aroundthe pn-junction J2 only through recombination of the charge carriers.For most applications, however, this occurs too slowly. With aninductive load, the current flows fully over the MOSFET M2 after theMOSFET M1 is closed, until the outer voltage is built up. Since then-base zone 3 is now connected to the anode contact A and the MOSFET M1no longer supplies any current, the switching off behavior of thecomponent is given by that of the n⁺ pn-transistor 1, 2, 3 with openbase. Since the power amplification factor and avalanche multiplicationfactor of such a transistor are considerably higher than for apnp-transistor, the thickness and also the specific resistance of then-base zone 3 are adjusted higher with a predetermined voltage to beswitched on than for a standard component that is controlled from thecathode side, e.g. the IGBT or the GTO thyristor.

In order to render the thyristor conductive while there is negativevoltage present at the cathode K relative to the anode A and while theMOSFET M1 is switched on, it is initially possible, as alreadymentioned, to design the thyristor such that it does not block in theforward direction without the bypass from the n-base zone 3 via M2 tothe anode connection A. For this, the sum of the power amplificationfactors α_(npn) +α_(pnp) is adjusted higher than 1 in the blockingcurrent range already. This can be achieved in practical operations inthat the degree of effectivity for the emitters is set high through arelatively high integral doping of the emitter zones and that thetransporting factors for the partial transistors are adjusted highthrough the lowest possible integral doping of the p-base zone 2 and ahigh carrier lifetime. The ICMT unit cell in that case switches to theon-state condition as soon as the voltage between gate G and anode A orbetween gate G and FE exceeds the threshold voltage.

To be able to proceed in this way, the emitter base junction J₃ cannotbe short-circuited, since the component blocks in a forward directionwith a short-circuited junction, even without the bypass through theswitched-on MOSFET M2. Corresponding measures were taken concerning thisin the inventive, bidirectional switching element, since the n-emitterzone 1 is missing in some sections of the structure and the junction J₃is short-circuited per se. In general, a thyristor that does not blockin the forward direction in the relatively broad temperature range thatis allowed has long switching times as a result of the required highcarrier lifetime. Also, the blocking capacity is reduced when the MOSFETM2 is switched on because of the high power amplification factorα_(npn). It is therefore often better to use a thyristor, which has aforward blocking capacity even if the bypass for the n-base is switchedoff through the MOSFET M2. In accordance with the invention, an ignitiongate is provided in that case to ensure that the thyristor switches tothe on-state condition once a positive voltage is applied to the gate G.

Such an ignition arrangement is shown in FIG. 2, wherein the sameelements in FIGS. 1 and 2 are given the same reference numbers. In aregion Z of the semiconductor component, which is separated from thefloating electrode FE either by a larger distance or throughinterruption of the p-emitter zone 4, a p-emitter zone 4' is providedwith the gate contact 12, which is connected via a resistor R with thegate connection G. A n⁺ -zone 10 that is embedded into the p-emitterzone 4' has a contact 11, which is connected to the floating electrodeFE, but which does not short-circuit the pn-junction J₆ between p-zone4' and n⁺ -zone 10 in the ignition region. With a positive voltage atthe gate opposite FE, not only is FE connected via the n-channel in theunit cells with the anode contact 8 and the anode connection A, but gatecurrent then flows into the p-emitter zone 4' of the ignition region,and the n⁺ -zone 10 injects electrons, which diffuse to the pn-junctionJ_(1') between p-emitter zone 4' and n-base zone 3 at the junctionJ_(1'). As a result of this, the pn-junction J_(1'), is polarized morein the on-state direction, so that the charge carrier concentration inthe n-base zone 3 at junction J_(1'), between the p-emitter zone 4' andthe n-base zone 3, is raised. As a result of the concentration gradient,holes diffuse toward the space charging zone RLZ around the pn-junctionJ₂, between n-base zone 3 and p-base zone 2 and are there pulled offthrough the field into the p-base zone 2. As a result of this, theyfunction as base current for the n⁺ pn-transistor 1, 2, 3 and actuateit. The collector current for this transistor flows into the n-base zone3 and actuates the pnp-partial transistor 4', 3, 2 of the thyristorstructure. As a result of this, more holes are flowing into the p-basezone 2 and the current increases until the thyristor is ignited. Thisignition gate is related to the "remote gate" arrangement used for theTriac. The switched-on condition then spreads in the known way over thesurface with the ICMT unit cells.

If the MOSFET M1 is switched off, then the current in the ignitionregion is also switched off. As for the unit cells according to FIG. 1,a MOSFET (M2') that connects the n-base zone 3 with the n⁺ -region 10 isadditionally provided to permit an efficient switching off.

When switching off the n-base zone 3, it is therefore connected via theswitched-on MOSFET M2, the floating electrode FE and the MOSFET M2 ofthe unit cells to the anode connection A. The thyristor 10, 4', 3, 2 ofthe ignition region is polarized in a forward direction for a reverseblocking stress of the ICMT. In general, it blocks only if no controlcurrent is fed to base 4' of this thyristor through positive voltage atgate G.

FIG. 3 shows another inventive arrangement for igniting the thyristorwith the zones 1, 2, 3, 4 while the MOSFET M1 is switched on. In thiscase, the p-base zone 2 at the edge of the semiconductor element isconducted via a p-border zone 20 to the upper limiting level or surfaceof the semiconductor element or body, as is already known in a similarway from thyristors that block on both sides. At the upper limitinglevel, the p-base zone 2 forms a region 24 into which a n⁺ -zone 5d isembedded. The p-region 24 is not separated in the standard way from theupper p-emitter zone 4 inside the semiconductor wafer or body by then-base zone 3 that emerges on the surface, but is connected with itthrough a p-channel zone 21 that is positioned at the surface. Thicknessand integral doping of the p-zone 21 are adjusted such that one eachdepletion-type p-channel MOSFET MZA or MZK is formed, together with anabove-arranged insulator and a gate electrode 9' that is installedtoward the chip inside, as well as a second gate electrode 22 thatextends from the border. The gate electrode 9' is connected to the outeranode contact 8. The gate electrode 22 simultaneously forms the contactlayer for the n⁺ -zone 5d, which is connected such that it conducts withthe cathode contact 7 on the lower limiting level or surface of thesemiconductor element. Furthermore, on the surface of the p-region 24,an inversion-type MOSFET M2' is integrated, between the n⁺ -region 5dand the p-channel zone 21.

With a forward polarization of the component V_(K) <V_(A) andswitched-on MOSFET M1, a current path leads from the anode contact 8 viathe floating electrode FE, the p-emitter zone 4, the p-channel zone 21and the border zone 20 to the p-base zone 2' of the thyristor 1, 2, 3,4. Hole current is fed into the p-base zone 2 via the current path, andthe thyristor 1, 2, 3, 4 is ignited. The ignited condition then spreadsfrom the border to the unit cells located on the inside. If the MOSFETM1 is switched off at V_(K) <V_(A), then the pn-junction J₅ is polarizedin blocking direction.

The inversion-type MOSFET M2 is switched on as a result and thedepletion-type MOSFET MZA is switched off. The n-base zone 2 is thusconnected to the anode contact 8, and the connection between the upperp-emitter zone 4 and the lower p-base zone 2 is interrupted. The voltageis essentially absorbed by the n⁺ pn-junction J₂, located betweencathode K and anode A. The p-channel zone 21 here is emptied of chargecarriers in the region outside of the MOSFET MZA, which leads to areduction in the electrical field at the surface.

In case of reverse polarization of the component, meaning the cathodepotential is greater than the anode potential (V_(K) >V_(A)), thepn-junctions J₁ and J₃ are polarized in blocking direction. Since thep-region 24 and the neighboring section of the n-base zone 3 have apositive polarization relative to the gate electrode, a n-channeldevelops on the surface of the p-region 24 and the p-channel for theMOSFET MZK disappears. The n-base zone 3 is thus connected with thecathode K. If the MOSFET M1 is switched on, the component blocks throughthe pn-diode 4, 3 and with switched-off MOSFET M1 through the n⁺pn-transistor 5b, 4, 3, wherein the pn-junction J₃ that absorbs only afew volts is connected in series. The p-zone 21 here is drained outsideof the MOSFET MZK of charge carriers. As a result of this, the expansionof the space charge zone around the pn-junction J₁ at the surface isincreased, and the surface field strength is reduced. As compared to theignition gate according to FIG. 2, the arrangement according to FIG. 3initially has the advantage that the component is switched on as well asoff through MOS gate.

Another advantage is that the reverse blocking capacity is improved byswitching on the bypass from the n-base zone 3 to the cathode K.

So that the MOSFET M1 remains switched off during the voltage build-uparound the pn-junction J₅ and the MOSFET M2 switches on, it is notsufficient that the potential for anode A is applied to the gate G,since in that case both MOSFETs would switch on once the voltage at thepn-junction J₅ exceeds the threshold voltage for the MOSFETs. Rather, itis necessary to apply to gate G a negative voltage relative to A, e.g. avoltage of -5 V. The MOSFET M1 then remains switched off while M2switches on, and the pn-junction J₂ starts to block.

If the voltage at the gate is set equal to zero, relative to the anode,the component must not necessarily switch off. Since the MOSFET M1 inthat case does not remain fully shut down, it would also no longerrepresent a pure cascode circuit.

If gate G has a fixed, predetermined voltage relative to the anode A,for example V_(G),A =10 V, then the component does not have a forwardcharacteristic with current limiting since the n⁺ -region 5b that isconnected to the anode A functions as the drain region for the MOSFET M1in the current-carrying ICMT. However, a MOSFET does not have a currentlimitation with fixed gate-drain-voltage. Yet, if the gate G is providedwith a fixed voltage relative to the floating electrode FE, then thisresults in a current limitation. As a result of the MOSFET M2 which isthen fully switched on, the n⁺ pn-transistor 1, 2, 3 with the blockingpn-junction J₂ then ensures a current limitation up to high voltages.

The inventive principles, which were described in more detail for thevertical components, can be applied in a simple way also to the lateralcomponents, for which both main electrodes, together with the controlelectrode, are arranged on the upper limiting level for thesemiconductor element. FIG. 4 shows a lateral embodiment of thecomponent according to FIG. 1, which can be switched on and off from theanode side. In addition to the anode and gate connection A' or G', thecathode connection K' and the cathode metallization 7' as well as thecathode emitter zone 1' with the surrounding p-base zone 2' of thethyristor structure 1', 2', 3', 4" are located on the surface of thesemiconductor element. On the bottom, the n-base zone 3' is separatedfrom the substrate below by an insulating layer (e.g. S₁ O₂) or even apn-junction. The anode metallization 8' and the cathode metallization 7'do not make contact with the p-zones 4" or 2', into which the contactingn⁺ -zones 5b" and 5a' are embedded. Since the p-base zone 2' is alsolocated on the upper main level, the p-base zone 2' and the p-emitterzone 4' of the thyristor 1', 2', 3', 4" are connected directly via thep-channel zone 21' which forms the depletion-type MOSFETs MZK', MZA',together with the oxide-overlapping metallizations 7', 8' for the anodeand cathode. As described in connection with FIG. 3, the componentblocks in the reverse direction, regardless of the gate voltage present,wherein the cathode-side MOS structure becomes effective and J₁ blocks.

With a forward polarization (V_(K) <V_(A)) and switched off MOSFET M1',the component blocks in a totally analogous manner. If the MOSFET M1' isswitched on and the anode A thereby connected to the p-emitter zone 4",then the thyristor 1', 2', 3', 4" is ignited by the hole current flowingvia the p-channel zone 21' into the p-base zone 2.

FIG. 5 shows a bidirectional switch, composed of the above-describedICMT unit cell 4 and an IGBT unit cell. The IGBT unit cell has thestandard structure described in the following. The lower p+-zone 2a isfollowed by a weakly doped n-base zone 3a, which has a p-trough 4a onthe surface, into which a n⁺ -zone 5c is embedded. The p+-zone 2a iscovered with a metallic contact layer 7a and the n⁺ -zone 5c as well asthe p-trough 4a with a joint metal layer 10a. A gate electrode 11a' islocated above the region for the p-trough 4a, between the n⁺ -zone 5cand the surface region for the n-base zone 3a. Together with theinsulated gate electrode 11a', the n⁺ -zone 5c, the surface region ofthe p-trough 4a and the n-base zone 3a form a n-channel MOSFET. The ICMTunit cell corresponds to the arrangement shown in FIG. 1. The thyristorcan be ignited by an arrangement according to FIG. 3 that is not shownin FIG. 5. As can be seen, both parts of the bidirectional switch, theICMT and the IGBT, can be produced with the aid of the same proceduralsteps, starting with a semiconductor wafer with n-doping. Only thelateral masking must be different, above all for the n⁺ -zones. Thelower contact electrodes 7, 7a serve both unit cells and are connectedto a main electrode connection E2. On the upper limiting lever orsurface, the anode electrode 8 of the ICMT and the cathode or sourceelectrode 10a of the IGBT are connected with an upper main connectionE1. The ICMT unit cells and the IGBT unit cells can also be arranged indifferent semiconductor components that are mutually connected by ahybrid circuit.

In FIG. 5, the gate electrode 6 of the ICMT and the gate electrode 11a'of the IGBT are connected by a joint outside gate connection G_(gem).However, the ICMT and the IGMT can also have separate gate connectionsG1 and G2 and can thus be actuated separately, which has certainadvantages that are described in more detail below. In contrast to theknown bidirectional switches, the two gates here are actuated by thesame reference electrode E1 or FE, which is why the control expendituredoes not increase as much in comparison to the case with a gate. In themonolithically integrated form, the two types of unit cells for thebidirectional semiconductor component according to FIG. 5 are eacharranged in a separate surface region of the semiconductor element orbody. As a result of being spaced apart relatively far, it is preventedthat the pn-junctions J₃ and J₁ of the ICMT part are short-circuited orthat the thyristor structure is switched on, which is formed by thep-zone 4a of the IGBT and the npn-zone succession 1, 2, 3 of the ICMTand cannot be switched off through the gate.

The operation of the bidirectional component is described with the aidof FIGS. 6a to 6d. In the first quadrant of the current-voltage level, apositive voltage U_(E2) is present at the lower main connection E2,relative to the upper main connection E1, which always has zeropotential, meaning U_(GE1) =0. With this polarization and regardless ofthe gate voltage that is present, the ICMT cell is blocking through thepn-junction J₁, between p-trough 4 (anode emitter) and n-base 3, asexplained above. If the voltage V_(GE1) of the gate is equal to zerorelative to E1, then the IGBT is also in the blocking condition, whereinthe voltage is again absorbed by the pn-junction J', between p-zone 4aand n-base 3a. This is indicated in FIG. 6a by the hatched areafollowing J₁, J₁ '. The combination component thus is in the forwardblocking condition, which is described by an operational point on theblocking characteristic in the first quadrant.

According to FIG. 6b, the voltage at the electrode E2 remains positive,e.g. +500 V. However, a positive voltage of, for example, 10 V is nowpresent at the gate G_(GEM), which is higher than the threshold voltagefor the MOSFETs. Thus, the IGBT switches in the known way to theon-state condition. In the ICMT cell, the floating anode connection ofthe thyristor is connected via the n-channel of MOSFET M1 with the mainconnection E1, to be sure. However, the thyristor continues to be in thereverse blocking condition, wherein the voltage has of course collapsedto the on-state voltage of the IGBT. The combined bidirectionalcomponent is in the forward on-stage condition, which is determined bythe IGBT.

If the electrode E2 is connected to a negative potential relative to E1,one is in the third quadrant. With this polarization, the IGBT blocksthrough the lower pn-junction J_(2') regardless of which gate voltage ispresent. If the MOSFET M1 is switched off, the ICMT blocks as well, thatis also through the pn-junction J₂ between n-base 3 and lower p-zone 2,as described in the above. This case is shown in FIG. 6c. The internalMOSFET M2 is switched on in this condition, so that the n-base zone 3 isconnected to the upper main connection E1 via the bypass X to theanode-side pn-junction J₁. As mentioned above, the breakdown voltage ofthe pn-junction J₅ must clearly be adjusted higher than the thresholdvoltage of the MOSFET M2 for this.

Since the switching off operation is determined by the lower n⁺pn-transistor 1, 2, 3, the thickness and specific resistance of then-zone 3a is adjusted higher than would be necessary for the IGBT alonein order to obtain a given, secure operating range during the switchingoff.

If, with continued negative potential at E2, the voltage at gate G israised to a value above the threshold voltage for the MOSFETs, then theIGBT remains in the blocking position, as already mentioned. In the ICMTunit cell, the emitter zone 4 of the thyristor is connected via thefloating electrode and the n-channel of the MOSFET M1 with the outerelectrode E1. As a result of this, the potential in the p-zone 4increases from the former negative value to nearly the value of zero ofelectrode E1, so that the n-channel in the MOSFET M2 disappears, meaningit is switched off. The thyristor 1, 2, 3, 4 must switch on at the sametime. It must be taken into consideration here that the n⁺ -zone 1 ismissing in the surface region with the IGBT cells and the pn-junction J3thus normally ends on the lower surface and is short-circuited by thejoint IGBT and ICMT metallization 7.

However, if the ignition occurs with the aid of the arrangementaccording to FIG. 3 or owing to the fact that the thyristor 1, 2, 3, 4is designed without forward blocking capacity, then the pn-junction J₃must not be short-circuited. For the embodiment of the inventivebidirectional switching element, the region of the lower limiting levelwith the pn-junction J₃ is covered with an oxide layer 12' or anotherinsulating layer to prevent the short-circuiting, as shown in FIG. 7.Even the p-zone 2 of the ICMT runs out shortly after the n⁺ -emitterzone 1 and ends in the surface region that is covered by the oxide, sothat it has no contact with the metallization 7 of the lower limitinglevel or surface of the semiconductor element.

The p-zone 2a of the IGBT starts at a distance from this and isseparated from the p-base zone 2 of the ICMT by the n-base zone 3 thatemerges on the insulating surface. The width for the n-base zone 3 onthe surface is so small that the blocking capacity of the pn-junction J₂is not impaired. The pn-junction J₃ can then be polarized in theblocking direction, which is necessary to the function of the design ofthe border according to FIG. 3. Also, the thyristor 1, 2, 3, 4 can nowbe dimensioned in the such a way that it does not block in forwarddirection without shorting through the internal MOSFET M2. Theseparation of the p-base zone 2 and the anode-side p-zone 2a of thecathode-side actuated component can also occur through a gap that isadvisably filled with insulating material.

A bidirectional component has been created with this, which isconducting with positive gate voltage, but which blocks withdisappearing or negative gate voltage. The component switches on if thegate voltage is increased to a value above the threshold voltage, whileit switches off if the gate voltage is lowered to zero or a negativevalue, that is with positive voltage of the lower electrode E2 relativeto E1 (first quadrant) as well as with negative polarization of E2relative to E1 (third quadrant).

In addition to the option of preventing the short-circuiting of junctionJ₃ and to design the thyristor 1, 2, 3, 4 as non-blocking in the forwarddirection, there is also the alternative option of using an ignitiongate according to FIG. 2. However, this gate has the characteristic thatit can switch on the upper thyristor structure 2, 3, 4, 10 of theignition region if the polarization is V(E2)>V(E1) and with positivegate voltage since control current is then fed into its p-base 4. Theignited condition cannot spread to the thyristor 5b , 4, 3, 2 of theunit cells, to be sure, since with positive gate voltage the emitterjunction J₅ of this thyristor is short-circuited by the inversionchannel of the floating electrode FE. However, the switched on ignitionregion cannot be switched off simultaneously with the IGBT by the MOSFETM1, owing to the parallel position of pn-junction J₅ with on-statepolarization. In order to prevent the switching on of the ignitionregion, it is therefore necessary when using this ignition gate toprovide the gate electrode 6 of the ICMT with its own gate connection G1and the gate electrode 11 of the IGBT with a separate gate connection G2and to actuate both with different control signals. In the firstquadrant (V(E2)>V(E1)) only the IGBT is then actuated with a positivegate voltage while the voltage at the ICMT gate G1 relative to FE isadjusted equal to zero or negative.

The embodiment shown in FIG. 8 of the ignition region of a bidirectionalcomponent, composed of an ICMT and an IGBT, makes it possible to actuatethe ICMT and the IGBT via a single gate connection G', even if anignition gate is required. For the polarization V(E2)<V(E1) of the mainelectrodes E1, E2, this gate G' causes a switching on of the thyristor1, 2, 3, 4 of the ICMT if a positive gate voltage is applied. ForV(E2)>V(E1), a positive gate voltage can be applied without the ICMTportion of the component being switched on.

The p-region that is provided with a gate contact 12 has its ownp-trough 4a', which is connected only by a p-channel 4c to thetrough-shaped p-region 4b, comprising the n⁺ -zone 10"' with electrode11" connected to FE. Together with an insulated electrode 13, locatedabove the p-channel, the regions 4a', 4c, 4b in connection with thesubstrate of the n-base zone 3 form a depletion-type p-channel MOSFETM2. Positioned in front of the p-region 4a' is an additional p-region 14with a contact 15, which region 14 is embedded like a trough in then-base zone 3. This contact 15 has a conducting connection to the gateelectrode 13 of the MOSFET MZ. With the assumed positive voltage at theelectrode E2, relative to E1, a space-charge zone RLZ forms around theblocking pn-junction J_(1") during the blocking condition of thecomponent, as drawn in Figure 8. As a result of this, the p-region 14has a positive potential relative to 4a'.

Owing to this potential at the gate electrode 13 and the voltage atsubstrate 3, the p-channel between the regions 4a' and 4b is made todisappear, so that no gate current can flow into the region 4b and canignite the thyristor 10"', 4b, 3, 2. In order to obtain a stableblocking behavior for this thyristor, another arrangement is provided inFIG. 8, which short-circuits the pn-junction J₆ between the p-zone 4band the n⁺ -zone 10" for the polarization VK>VA. This occurs with theaid of a n⁺ -zone 16, embedded as a trough into the p-zone 4b, which hasa contact 17 that simultaneously makes ohmic contact with the zone 4b.The n⁺ -zone 16, n⁺ -zone 10"' and the interposed p-region with theabove-arranged insulating gate electrode 18 form a n-channel MOSFET MS.The gate 18 of this MOSFET is connected to the p-zone 14 installed infront and therefore has a positive potential relative to the regions 4band 16 if the polarization of the main electrode is V_(K) >V_(A). Thus,the MOSFET MS is switched on and connects the n⁺ -region 10 low-ohmicwith the p-zone 4b. The blocking capacity of the component for V_(K)>V_(A) is improved considerably if the short-circuit of the pn-junctionJ₆ is switched on.

The thyristor comprising 1, 2, 3, 4 is switched on through the ignitiongate structure shown in FIG. 8 if V(E2)<V(E1). However, the thyristorstructure 2, 3, 4b, 10 is not ignited in the first quadrant where it ispolarized in the forward direction. The blocking behavior isadditionally stabilized in the first quadrant owing to the fact that theshort-circuit for the pn-junction J₆ is switched on.

If a current limiting characteristic is required for the bidirectionalswitch, then this can be achieved by actuating the gate G in FIG. 8 notwith a fixed voltage relative to the main connection E1, but relative tothe floating electrode FE. It follows directly from the explanations forthe ICMT that this is the case for the third quadrant at V(E2)<V(E1).However, this is also the case for this actuation in the first quadrant,since the electrode FE with positive gate voltage V_(G),FE ispractically lying at the potential of E1 since the switched-on MOSFET M1carries only the current for the thyristor blocking in reversedirection. If V_(G),FE =0, then the component, in this case the IGBT, isalso placed in the blocking position. The electrode FE in that caseassumes a potential relative to E1, which is provided by the voltage ofthe pn-junction J₅ that has a weak forward polarization owing to theblocking current. For example, FE and thus also G has a potential of 0.3V relative to E1 if V_(G),FE =0, while the threshold voltage incomponents of this type typically has values around 3 or 4 V, so thatthe IGBT blocks. Thus, if the gate is controlled with a fixed voltagerelative to the floating electrode, then the bidirectional component hasthe desired features, in particular it has a characteristic with currentlimitation in the first as well as the third quadrant.

For an embodiment with two different gates, which here are actuated fromthe one main electrode E1, as opposed to the known bidirectionalswitches, another important advantage can be achieved in addition to theusability of the simpler ignition structure according to FIG. 2, inplace of FIG. 8. This advantage consists of being able to combine thefull bidirectional switching ability in one single unit cell. Thispermits using one and the same surface for carrying the current in bothdirections, so that the required semiconductor surface is reducedconsiderably as compared to the case with only one gate connection. Sucha unit cell that is bidirectional in itself is shown in FIG. 9. Itdiffers from the ICMT unit cell according to FIG. 1 only in that thegate for MOSFET M2 is not fixedly connected to the outer electrode A(E1' in FIG. 9), but is separate from it and can be actuated from theoutside via a separate gate connection G2.

In accordance with the embodiment shown in FIG. 9, a short-circuiting ofthe pn-junction J₃ is prevented with the aid of an oxide layer 12".Since the thyristor structure 1, 2, 3, 4 is supposed to conduct well inthe third quadrant, which is however impaired by the junction J₃ thatfunctions as collector, the lateral expansion of the n⁺ -emitter zone 1as well as the p-zone 2a must be greater than the lateral cell pitch.The surface regions having only one p-zone 2a below and the regionswhich also have a n⁺ -emitter zone 1 can also alternate in "stripdirection," perpendicular to the drawing plane. If the MOSFET M1 isswitched on, then the component functions like an IGBT that is switchedby the gate G2. If G2 is connected to E1, then the function of an ICMTswitchable through gate G1 is obtained.

Thus, for V_(E2) >V_(E1) in the first quadrant, the gate E1 is lying ata positive potential relative to E1 (or FE), so that the MOSFET M1 isswitched on. The thyristor 1, 2, 3, 4 then has reverse polarization, andthe right portion of the structure, namely 2a, 3, 4, 5b together withthe MOS gate G2 behaves like an IGBT. The component switches on with apositive voltage at G2 relative to E1. If the voltage is lowered tozero, then it switches off. In the third quadrant, for V_(E2) <V_(E1),G2 is connected to the electrode E1', so that the component functionslike the ICMT in FIG. 1. It can be switched on and off by actuating thegate G1, as is described there.

The fact that the n⁺ -base zone 1 like the p-emitter zone 2arespectively covers only a portion of the lower limiting surface doesnot essentially interfere with the function of the ICMT or the IGBTsince the base zone 3 is considerably thicker than the lateral expansionof the gap in the lower n-emitter zones 1 and the zone 2a for the ICMTor the IGBT function.

The MOS inversion channels on the upper main level of the semiconductorelement are nevertheless effective over the total channel width, meaningthe expansion perpendicular to the drawing plain. Thus, a bidirectionalcomponent has been created with relatively small surfaces andsimultaneously wide channel width. Thus, neither the channel resistancenor the on-resistance inside the semiconductor are raised significantlywhile the active component surface is cut nearly in half.

Analogous to FIG. 5, the anode-side controlled, lateral componentaccording to FIG. 4 can be combined with standard components, e.g. alateral IGBT with unit cells arranged in another surface region, to forma lateral bidirectional semiconductor element. The gate electrodes forboth individual components as a rule have a joint gate connection. Asdescribed with the aid of FIG. 6, the component is switched on withpositive gate voltage and switched off with negative or disappearinggate voltage, independent of the polarity of the main electrodes.

We claim:
 1. An anode-side actuated semiconductor component, including asemiconductor element which has a plurality of side-by-sideparallel-connected unit cells with a thyristor structure, and with thethyristor structure of a unit cell including higher doped p-zones,including a p-base zone (2) and a p-emitter zone (4) bordering onopposite sides of a weakly doped n-base zone (3); and where the p-basezone (2) borders on a highly doped n-emitter zone (1), which makescontact with a cathode electrode (7); and wherein for each unit cell:the p-emitter zone (4) is trough shaped and formed in the n-base zoneadjacent one major surface of the semiconductor element; a first and asecond n⁺ -zone (5a, 5b) are embedded, at a distance from each other inthe p-emitter zone (4) adjacent the one major surface; the first andsecond n⁺ -zones (5a, 5b) together with a p-region portion of thep-emitter zone (4) that exceeds to the one major surface in-between thefirst and second n-zones and an insulated first gate electrode (6)disposed on the one major surface above the p-region portion form afirst n-channel MOS field effect transistor (M1), which is connected inseries with the thyristor structure through a floating electrode (FE);the second n⁺ -region (5b) is adjacent an edge of the trough-shapedp-emitter zone (4) and together with a portion of the n-base zone (3)that extends to the one major surface adjacent said edge, a region ofthe p-emitter zone (4) extending to the one major surface between thesecond n⁺ -zone and the n-base zone and a second gate electrode (9)arranged on the one major surface over the region of the p-emitter zoneform a second n-channel MOS field effect transistor (M2); and a drainelectrode of the first MOSFET (M1), which makes contact with the secondn⁺ -zone (5b), simultaneously forms an outer anode electrode (8), whichis separated from the p-emitter zone (4) by an insulating layer. 2.Semiconductor component according to claim 1, wherein the unit cells aresubdivided by a trough-shaped design for the p-emitter zone (4). 3.Semiconductor component according to claim 1, wherein: a verticalembodiment of the thyristor structure is provided with the n-emitterzone (1), the p-base zone (2), the n-base zone (3), the p-emitter zone(4), and the anode electrode (8) being arranged one above the other; andthe cathode electrode (7), which is connected to the n-emitter zone (1),is arranged on a lower limiting level or major surface of thesemiconductor element and the anode electrode (8) as well as the firstgate electrode (6) are arranged on the upper limiting level or one majorsurface of the semiconductor element.
 4. Semiconductor componentaccording to claim 1, wherein: at a distance from the floating electrode(FE) or separated from it by an interruption in the p-emitter zone, anignition region is arranged in the semiconductor element, with theignition region comprising a p-emitter zone (4'), a therein embedded n⁺-zone (10) of the n-base zone (3) that borders the p-emitter zone (4'),the adjoining p-base zone (2) and the following n-emitter zone (1); thep-emitter zone (4') of the ignition region has an ignition-gate-contact(12), which is connected via a resistor with the first gate electrode(6); and the embedded n⁺ -zone (10) is provided with a contact electrode(11) that is connected to the floating electrode (FE), but which doesnot short-circuit the pn-junction (J6) in the ignition region betweenthe p-emitter zone (4') of the ignition region and the embedded n⁺ -zone(10).
 5. Semiconductor component according to claim 1, wherein: thep-base zone (2) is carried to the upper limiting level or one majorsurface by a p-border zone (20) of the semiconductor element and thereforms a p-region (24), into which a further n⁺ -zone (5d ) is embedded,which further n⁺ -zone is connected conductively with the cathodeelectrode (7); the p-region (24) and the p-emitter zone (4) areconnected on the surface by a p-channel zone (21) which, together withthe gate electrode (9') of the second MOS field effect transistor (M2)that overlaps the p-channel zone (21) at the edge of the p-emitter zone,forms a depletion-type p-channel MOS field effect transistor (MZA); athird insulated gate electrode (22), which is connected conductively tothe cathode-side contacted further n⁺ -zone (5d) and overlaps thechannel zone (21) at the edge of the p-region (24), forms an additionaldepletion-type MOS field effect transistor (MZK); and, a MOS fieldeffect transistor of the inversion type (M2") is formed from thecathode-side contacted further n⁺ -zone (5d) and the p-region (24) thatextends to the one major surface, together with the third insulated gateelectrode (22).
 6. Semiconductor component according to claim 1,wherein: the n-base zone (3') is arranged on a substrate (5), separatedfrom it by one of an insulating layer or a pn-junction; the p-base zone(2') and the p-emitter zone (4") are arranged in respective troughshapes in the n-base zone (3), at a lateral distance from each otherthat is predetermined by the blocking capacity; and the n-emitter zone(1') is arranged in the p-base zone (2') and the source and drain zones(5a', 5b') for the first MOS field effect transistor (M1') are arrangedin the p-emitter zone (4").
 7. Semiconductor component according toclaim 6, wherein: the p-base zone (2') and the p-emitter zone (4") areconnected at the one major surface by a p-channel zone (21') which,together with the insulated gate electrode (9') of the second MOS fieldeffect transistor that overlaps the p-channel zone (21') at the edge ofthe p-emitter zone (4"), form a depletion-typdepletion-type MOS fieldeffect transistor (MZA') and which, together with a gate electrode (22')that is connected to the cathode electrode (7'), forms an additionaldepletion-type p-channel MOS field effect transistor (MZK'); and aninversion-type n-channel MOS field effect transistor (M2") is formed bythe n-emitter zone (1') and the p-base zone (2'), which extends to theone major surface, together with the gate electrode (22') that isconnected to the cathode electrode.
 8. A bidirectional semiconductorcomponent comprising an anode-side actuated semiconductor component(ICMT) according to claim 1 and a cathode-side gate actuated component(IGBT) in a hybrid circuit; and wherein the anode connection of theanode-side actuated semiconductor component (ICMT) and a cathodeconnection of the cathode-side actuated semiconductor component (IGBT)are combined to form a single first main electrode (E1); and the cathodeof the anode-side actuated semiconductor component (ICMT) and an anodeof the cathode-side actuated semiconductor component (IGBT) are combinedto form a second main electrode (E2).
 9. A bidirectional semiconductorcomponent according to claim 8, wherein: the gate electrode (11a') ofthe cathode-side actuated semiconductor component (IGBT) and the gateelectrode (6) of the first MOS-FET (M1) of the anode-side actuatedsemiconductor component (ICMT) are combined to form a joint gateelectrode (G_(gem)).
 10. A bidirectional semiconductor componentcomprising an anode-side actuated semiconductor component (ICMT)according to claim 1 and a cathode-side actuated semiconductor component(IGBT); and wherein: the unit cells of the anode-side actuatedsemiconductor component (ICMT) are monolithically integrated in thesemiconductor element with unit cells of the cathode-side actuatedcomponent (IGBT); and the unit cells of the anode-side actuatedsemiconductor component (ICMT) are arranged in a first surface regionand the unit cells of the cathode-side actuated semiconductor component(IGBT) are arranged in a second surface region of the semiconductorelement.
 11. A bidirectional semiconductor component according to claim10, wherein: in the second surface region, the unit cells of thecathode-side actuated semiconductor component form an insulated gatebipolar transistor (IGBT) with an anode-side p-zone (2a), a n-base zone(3a) and a cathode-side p-zone (4a), into which is embedded anadditional n⁺ -zone (5c), which forms a MOS field effect transistortogether with the n-base zone (3a), the p-zone (4a) and an insulatedgate (G); and the cathode-side electrode (10a) is connected to theanode-side electrode (8) of the anode-side actuated semiconductorcomponent.
 12. A bidirectional semiconductor component according toclaim 10, wherein: the gate electrode (11a') of the cathode-sideactuated semiconductor component (IGBT) and the gate electrode (6) ofthe first MOS-FET (M1) of the anode-side actuated semiconductorcomponent (ICMT) are combined to form a joint gate electrode (G_(gem)).13. A bidirectional semiconductor component according to one of theclaim 10, wherein: said component is formed from a single group ofbidirectionally switchable unit cells but with sections of the n-emitterzone (1) and the p-base zone (2) being replaced by a p-zone (2a) thatborders the cathode metallization and which is separated from then-emitter zone (1) and the p-base zone (2); the anode metallization andthe cathode metallization of the component are connected to a first anda second main electrode (E1', E2'), and that the first and second MOSfield effect transistor (M1, M2) have externally actuated gates (G1,G2); given a conductive connection of the gate (G2) and the second MOSfield effect transistor (M2) with the first main electrode (E1'), thecomponent is an anode-side actuated semiconductor component (ICMT), andfor a positive actuation of the gate (G1) of the first MOS field effecttransistor (M1), the component is a cathode-side actuated insulated gatebipolar transistor (IGBT).
 14. A bidirectional semiconductor componentaccording to claim 10, wherein: an anode-side actuated component isarranged in the first surface region of the semiconductor element and alateral insulated gate bipolar transistor (IGBT) is arranged in thesecond surface region of the same semiconductor element; and the gate ofanode-side actuated unit cells and the gate of cathode-side actuatedunit cells are combined to form a single gate.
 15. A bidirectionalsemiconductor component according to claim 10 wherein: an ignition gateis provided in a region separate or at a distance from the first surfaceregion, with the ignition gate comprising the n-base zone (3) into whicha trough-shaped p-zone (4a') with a gate electrode (12) is embedded,which is connected to the gate electrode (6) of the anode-side actuatedcomponent and which furthermore has a second p-zone (4b), embedded inthe n-base zone (3), that is connected by a depletion-type MOS fieldeffect transistor (MZ) with the p-zone (4a') and comprises an additionaln⁺ -zone (10") with a contact electrode (11") which is connected to thefloating electrode (FE), and the gate electrode of the depletion-typeMOS field effect transistor (MZ) is connected to the contact electrode(15) of a p-zone (14), additionally embedded in the n-base zone (3),which is located in the space-charge zone around a pn-junction (J1") forthe reverse blocking operation of the anode-side actuated component(ICMT).
 16. A bidirectional semiconductor component according to claim15, wherein: a further additional n⁺ -zone (16) is embedded into thesecond p-emitter zone (4b), which has a joint, floating short-circuitingcontact (17) with the p-emitter zone (4b); and the two additional n⁺-zones (10", 16), together with the p-region portion of the p-zone (4b)extending between the two additional n⁺ -zones and a gate electrodedisposed on the one major surface over the p-region extending betweenthe two additional n⁺ -zones, form a n-channel MOS field effecttransistor, the gate electrode (18) of which is connected to the contactelectrode (15) of the p-region (14).
 17. A bidirectional semiconductorcomponent according to claim 10, wherein: in the border region betweenthe first and second surface regions, the n-emitter zone (1) and thep-base zone (2) of the anode-side actuated semiconductor component(ICMT) are separated from the anode-side p-zone (2a) of the cathode-sideactuated semiconductor component (IGBT) in the first surface region, andare separated from each other in the second surface region.
 18. Abidirectional semiconductor component according to claim 17, wherein:the p-base zone (2) of the anode-side actuated semiconductor component(ICMT) and the anode-side p-zone (2a ) of the cathode-side actuatedsemiconductor component (IGBT) end at a distance from each other and areseparated by a portion of the n-base zone (3) that extends in-betweensame at the lower limit or major surface of the semiconductor element;and the p-base zone (2) that extends to the lower major surface and then-base zone (3) are insulated against the metallization on the lowermajor surface of the semiconductor element by an insulating layer (12').19. A bidirectional semiconductor component according to claim 17,wherein: the p-base zone (2) of the anode-side actuated component (ICMT)and the anode-side p-zone (2a) of the cathode-side actuated component(IGBT) are separated by a gap which is integrated into the semiconductorelement, and which is filled with insulating material.